1. Field of the Invention.
The present invention relates to devices for the assembly of chain saw chains, and particularly to a device for the head spinning of a rivet in such chains.
2. Description of the Prior Art.
The saw chains used on chain saws include the chain elements of drive links, cutters, pre-set tie straps and tie straps. These elements are held together by a plurality of rivets which typically have a "head" pre-formed at one end prior to assembly, with the other end of the rivet being formed or headed after the chain elements have been put together. Such saw chains are typically shipped to chain saw distributors in the form of 100-foot reels. A distributor will then in turn ship the saw chain to its dealers in one of two forms--reel form or loop form. The dealer then supplies the end user or consumer with the saw chain in loop form for use on a chain saw.
A loop of saw chain is a specific length of chain for a specific type of chain saw, and is formed from the original 100-foot saw chain reel. To form such a loop, at least one of the rivets in the original reel must be removed to permit disassembly of the chain elements. Once a loop of desired size has been separated from the reel, the ends of the loop must then be reattached with a new rivet for use on a chain saw.
Examples of devices for heading rivets on chains in a chain manufacturing facility are shown in U.S. Pat. No. 3,182,441, granted to Simmons et al. on May 11, 1965 and U.S. Pat. No. 542,454, granted to Weibel et al. on July 9, 1895. Other orbital forming devices for automatically heading rivets on a high production scale are similar to those orbital forming machines or orbital riveters of VSI Automation of Detroit, Mich. and Black & Webster, Inc. of Waltham, Mass. Rivets are headed by these devices by providing an abutting surface on the pre-formed head of the rivet and engaging the unformed end of the rivet by a rapidly spinning member which is shaped so that when pressure is exerted by the spinning member along the axis of the rivet, a head is formed at the end of the rivet to secure the rivet about the elements of the chain.
A distributor or dealer does not require a high production device for rivet head spinning such as those described above. All that is required is an efficient and easy-to-use device for the occasional attachment of the ends of a loop together to form a saw chain loop for a chain saw. To this end, a number of manual rivet spinners have been designed. Typical of those rivet spinners are the table or benchtop chain rivet spinners manufactured by Herr Manufacturing Company of Tonawanda, N.Y. and the Oregon Saw Chain Division of Omark Industries, of Portland, Ore. Another manufacturer of such devices is Efco Industries of Piano, Italy. These manual rivet spinners have a spin head rotatably mounted on a base and an engagement member spaced axially from spin head for engaging the already formed head of the rivet to be headed. The rivet is entrapped between these two heads, and the operator manually rotates the spinning head to form the rivet head while at the same time forcing the engagement head toward the spinning head to maintain a compression force along the rivet's axis. These devices are quite slow in operation, because of the time required to align the chain and position the heads. In addition, the operator must use two hands for the spinning operation.
Efco Industries also manufactures a rivet spinner device which it calls "Electric Bench Rivet Spinner." This device has a floor stand, at the upper end of which is a vertical spindle rotated by an electric motor. A rivet to be headed is placed on a support plate and the lower end of the spindle is lowered into engagement with the unformed end of the rivet while the motor is turning the spindle to form the rivet head. The device is apparently operated by means of a foot pedal arrangement adjacent the floor. This control arrangement and the floor stand upon which the rivet spinner is mounted necessarily require extra floor space for accommodating this machine. These features also make it impossible to mount this rivet spinner on an existing bench for table top use.
A different type of tool for assembling chains is shown in U.S. Pat. No. 3,135,141, granted to Aitken on June 2, 1964. With this device, the rivet to be worked is positioned on a base with its axis aligned generally vertically. Spaced above the base is a rotatable shaft, the lower end of which can be lowered into engagement with the rivet by a handle secured to a cam located at the upper end of the shaft. The shaft is spun manually by a handle extending normally thereto, so that the operation of this device as a rivet spinner requires the use of two hands.
Two other manual chain assembly devices are shown in U.S. Pat. No. 3,233,402, granted to Urbaitis on Feb. 8, 1966 and U.S. Pat. No. 3,182,442, granted to Granberg on May 11, 1965. Both of these devices are hand held, with the Urbaitis device being small enough in size to be carried in a pocket. The Granberg device has a vice-grip type action for engaging the chain rivet being worked. Neither of these devices provides suitable stability, reliability or rivet head forming capability.
The manual rivet spinners presently in use are very laborious and time consuming for an operator, which raises the cost of such services when provided by distributors and/or dealers of saw chains. The present invention provides a bench or table top saw chain assembly device suitable for high quality, low production operation. After the saw chain has been positioned for work, only one hand of an operator is required to manipulate the device. In addition, the device is quite simple to use, only turning its motor on for rivet spinning when the operator has manipulated its handle.